A fuel injection valve of an electromagnetic type that is driven by an electrical signal from an engine control unit has widely been used in internal combustion engines of automobiles and the like.
As the fuel injection valve of this type, a port injection type that is attached to an intake pipe and indirectly injects fuel into a combustion chamber and a direct injection type that directly injects the fuel into the combustion chamber are available.
In the latter direct injection type, a spray shape defined by the injected fuel determines combustion performance. Thus, the spray shape needs to be optimized in order to obtain the desired combustion performance. Here, the optimization of the spray shape can be restated as a spray direction and a spray length.
As the fuel injection valve, a fuel injection valve including: a valve body provided to be slidable; drive means for driving the valve body; a valve seat which the valve body comes in contact with or separates from; and plural orifices provided on a downstream side of the valve seat, in which the plural orifices are formed in different angle directions with respect to a center axis of a nozzle has been known (see PTL 1). It has been known that a spray spouted from the fuel injection valve is substantially spouted in an axial direction in which an injection hole is processed. It is desired to increase processing accuracy in a direction of the injection hole for a type of fuel injection valve with plural injection holes (orifices) like the fuel injection valve described in PTL 1. It is also desired to control the length of the spray, which is spouted from each of the injection holes, to be short in order to avoid interference thereof with size of the inside of the combustion chamber, a shape of a piston surface, and air-control valves (an intake valve and an exhaust valve) as much as possible and to reduce a chance of production of exhaust gas components (particularly, soot and the like that are components of unburned gas).
The spray lengths of the plural injection holes are not taken into consideration for the fuel injection valve described in PTL 1. It is considered to change hole diameters of the plural injection holes as a method for controlling the spray length of each of the injection holes. In general, while a dimension of the hole diameter is set large for the injection hole that requires the long spray length, the dimension of the hole diameter is set small for the injection hole that only requires the short spray length. In this way, the spray length of each of the injection holes can be controlled.